Wastes discarded from the food industry, the stockbreeding and an ordinary household include large quantities of organic substances, and almost organic wastes are collected in a liquid, slushy or slurry-like condition. For example, as organic wastes there are a beverage, milk, pasteurized milk or other dairy products which have expired a consume-by date and thus been discarded from a shop, a waste liquid from the Shouchu industry, strained lees of an orange, an apple or other fruits discarded from the fruit juice industry, bean-curd refuse as a by-product during a bean curd process, sake lees produced during processing of Japanese rice wine (sake), oil cake, feces and urine of cattle discarded from a breeding farm or a pasture of a stock farmer, garbage from a household, a hotel and a restaurant, sludge from a biodegradation system and so on. These organic wastes may be recycled as a fertilizer in some cases, but they are almost incinerated in a garbage dump.
Since these wastes contain various kinds of ingredients, when being recycled as a fertilizer, it is preferable to process them into forms of dry powders, granules, pellets and so on. Therefore, it is necessary to finely crush them or smash them. Thereupon, it is also necessary for enhancing drying-up or granulation to finely crush or smash relatively long fibers of leaf-strings or roots of vegetables or straws mixed in cattle feces, hard bones, oils and fats contained in those wastes. Furthermore, since those wastes contain much water, the crushing and smashing is required to be carried out within a liquid or in a dripping wet condition.
Accordingly, as a wet method for smashing organic substances, a prior art utilizing a cavitation action is disclosed in the patent document of Japanese Patent Laid Open Publication No. 11-319819. The prior device has a water injection nozzle disposed within a box-like casing on one side so as to be directed toward inside, and air is sucked into a water jet to positively generate cavitation bubbles therein while the water jet is discharged through an opening on the other side, so that cells of organic granular substances can be broken by cavitation action of the water jet and gas-liquid separation can be attained.
In another reaction device utilizing a cavitation action as disclosed in the patent document of Japanese Patent Laid Open Publication No. 2001-017988, a high-pressure water jet nozzle and a target plate having a concaved surface disposed on the opposed side to the nozzle are fixedly arranged within a water such as a water in a pond or the like. Between the nozzle and the target plate, high-pressure water jet is produced so as to circulate autonomously and accompany with cavitation bubbles, so that by the cavitation produced there, organic granular substances suspended in the water can be dissolved and cell membranes of bacteria can be broken, resulting in purification of the water in the pond for a long time.
In the high-speed water flows injected from the water injection device, the cavitation action is generated to apply strong forces such as shear, tension, compression and so on to cells of the bacteria so as to cut and shatter the cells. The cavitation has such a capability as to break cells of plants, namely hard tissues or fiber constructed by the cells, which can be utilized in the shattering of the above-mentioned wastes.
In the former prior art, though comparatively soft organic granular substances such as the bacteria cells can be broken by breaking forces generated by the high-speed water flows, the breaking forces acting only instantaneously don't continue and thus are low in efficiency and lack of practical use with respect to the plant tissues, fibered tissues including hard portions of animals and a large mass. Especially, it is difficult to supply the plant fibers or lump-like substances effectively into the jet water flows. When processing animal wastes, especially containing fats, fats and oils are separated and suspended in a water to often make filter doggy and to shut down the device resultantly. Therefore, it is difficult to operate the device continuously and effectively for a long time.
Further, since metallic component members of the casing is repeatedly subjected to an erosion, a corrosion and/or large impact accompanied with the cavitation produced by a continuous operation of the device within the casing, it is necessary to take a countermeasure for repeat fatigue failures of the component members considering their material characteristics and a construction of the casing.